BODIPY-based carbon dots as fluorescent nanoprobes for sensing and imaging of extreme acidity

Abstract

Two kinds of novel water-soluble carbon dots (CD-A and CD-B) were synthesized from 4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives, and their abilities for sensing pH under extremely acidic conditions were studied. The fluorescence of CD-A is linearly proportional to the extreme acidity range of 1.5–4.0 with a pK_a of 2.90, while CD-B exhibits a linear response over the pH range of 1.0–4.0 with a pK_a value of 2.63. In addition, both CD-A and CD-B were successfully applied to visualize extreme acidity in bacteria. The results demonstrate that CD-A and CD-B can serve as promising nanoprobes for the determination of extremely acidic pH values with excellent biological significance.